Heretofore, a wireless charge system disclosed in Patent Literature 1 has been known which is configured to wirelessly supply power to a vehicle equipped with a battery (electric load) to charge the battery. This Patent Literature 1 discloses that, in a case where a plurality of power transmission devices are present, a power transmission coil is weakly excited to generate a random signal, which is detected by a vehicle, and the vehicle and the power transmission device are paired with each other if it is confirmed that the random signals match each other between the vehicle and the power transmission device.